1. Field of the Invention
The present invention relates to a magnetic disk medium and more particularly to a magnetic video recording disk in which magnetic particles are oriented substantially uniformly relative to each other and to the surface of the disk. The invention further relates to magnetic recording and reproducing apparatus for use with a magnetic recording disk to reproduce a picture in slow motion while minimizing so-called guard band noise by minimizing displacements of the path of the transducer. from the track being played back.
2. The Prior Art
In U.S. Pat. No. 3,509,274 there is disclosed apparatus for recording and playing back video signals using a disk with magnetic material thereon as the recording medium. A motor causes the disk to rotate and a lead screw is coupled to the rotating apparatus and to the main recording and playback transducer to cause the latter to follow a spiral track while recording video information on the disk. The transducer is caused to follow a slightly different path during playback of the recorded signals, the path being generally similar to one section of the track on which the signals are recorded but differing slightly therefrom and having certain portions in which the track and the path coincide more closely than at other portions. The apparatus has additional transducers that follow only a circular track and are connected to the main transducer at least during playback to record the signal reproduced by the main transducer during such times and a further transducer to playback signals recorded on the circular track. Such signals may be played back repeatedly while the main transducer is moved radially across the recorded part of the disk at a slower rate than normal to effect slow motion playback of signals on the spiral track. This slow radial movement causes the main transducer to follow a tighter spiral track than the normal one. The operation of the main transducer is controlled so that it supplies signals to the additional transducers primarily only when the main transducer is on those parts of its slow motion track that correspond more nearly to the track on which the signals were originally recorded, thereby providing as good a signal-to-noise ratio as possible.
However, in the prior patent, it was not recognized that the orientation of the magnetic medium on the disk affects the operation of the apparatus, especially during playback. Therefore, the prior patent shows no means for making sure that the area in which the track followed by the main transducer during slow motion playback most closely coincides with the original recording track at positions specifically related to orientation of the magnetic particles on the surface of the recording disk.
Accordingly, it is one object of the present invention to provide a novel magnetic recording medium.
It is another object of the present invention to provide a magnetic recording disk in which magnetic particles are orientated uniformly in a predetermined direction.
It is a further object of the present invention to provide magnetic recording and playback apparatus for use with a specific magnetic recording medium to produce a slow motion picture with less noise, particularly of the so-called guard band type of noise.
It is a further object of the present invention to provide magnetic recording and reproducing apparatus for use with a magnetic recording disk and in which the apparatus produces a picture of good quality from information recorded near the center of the disk so that deterioration of the reproduced picture will not be noticeable.
It is a still further object of the present invention to provide improved magnetic recording and reproducing apparatus using a magnetic disk as the recording medium to reproduce a picture in slow motion with better quality than has been possible heretofore.
These and other objects, features, and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings.